Powder collector construction

ABSTRACT

A construction for collecting excess powder in a system which involves the application of powder to a moving surface such as the surface of sheets issuing from a printing press. The collecting construction is located adjacent the powder applicator to pick up powder which does not attach itself to the sheets or other surfaces to thereby reduce the amount of powder entering the surrounding atmosphere. The collecting means comprise a plurality of modules with each module including enclosing walls with inlet and outlet openings being provided. The modules are supported in end-to-end relationship adjacent the applicator and conduits are provided for the passing of powder from the modules to a suction system.

United States Patent [1 1 Mowbray POWDER COLLECTOR CONSTRUCTION [75] Inventor: Kenneth D. Mowbray, Des Plaines,

Ill.

[73] Assignee: Electro Sprayer Systems, Inc.,

Rosemont, Ill.

[22] Filed: Dec. 17, 1973 [21] Appl. No.1 425,334

[52] US. Cl. 118/312; 118/70; 118/326 [51] Int. Cl B05b 15/04; B05C 11/10 [58] Field of Search 118/312, 70, 602, 610,

118/326; 15/300 R, 301; 98/115 SB [56] References Cited UNITED STATES PATENTS 2,897,743 8/1959 Marantz 118/326 3,027,588 4/1962 Bierstock 15/301 3,520,278 7/1970 Blackwell 117/326 3,628,213 12/1971 Ramo 15/301 3,680,528 8/1972 Sanders 118/50 3,719,030 3/1973 Blankemeyer et a1. 98/115 SB [4 1 May 13,1975

Primary Examiner-Mervin Stein Assistant ExaminerDouglas Salser Attorney, Agent, or Firm-McDougal1, Hersh & Scott [57] ABSTRACT A construction for collecting excess powder in a system which involves the application of powder to a moving surface such as the surface of sheets issuing from a printing press. The collecting construction is located adjacent the powder applicator to pick up powder which does not attach itself to the sheets or other surfaces to thereby reduce the amount of powder entering the surrounding atmosphere. The collecting means comprise a plurality of modules with each module including enclosing walls with inlet and outlet openings being provided. The modules are supported in end-to-end relationship adjacent the applicator and conduits are provided for the passing of powder from the modules to a suction system.

18 Claims, 9 Drawing Figures POWDER COLLECTOR CONSTRUCTION This invention generally relates to constructions utilized for collecting powder to thereby reduce the amount of powder present in the atmosphere. The invention is particularly directed to a powder collecting construction for use in association with applicators which apply powderto moving surfaces such as the surfaces of sheets passing from a printing press.

Electrostatic powder sprayers are widely employed as a means for applying anti-offset powders to the printed surfaces of sheets, webs and the like after issuing from a printing press. Typically the powder employed comprises a random mixture ranging in'size from to 100 microns. In practice particulate of a size of microns or greater will, due to the influence of the applicator and gravity, be applied to the surfaces and provide the offset protection. Smaller particles, however, have a tendency to become airborne particularly due to the air currents which may be generated by the printing machine and by conveying systems used for the printed material.

Attempts have been made to provide structures for purposes of removing at least substantial amounts of the powder from the atmosphere surrounding the applicator to thereby minimize the nuisance. An apparatus for removing powder is described in Sanders US. Pat. No. 3,680,528.

It is a general object of this invention to provide a highly effective means for achieving powder removal in conjunction with a system involving the application of powder to printed surfaces and the like.

It is a more specific object of this invention to provide a construction for powder removal which is highly versatile in nature in that the construction can be effectively utilized in conjunction with systems of various sizes. g

It is a still further object of this invention to provide a construction of the type described which can be readily modified to accommodate different needs whereby maximum effectiveness can be achieved without encountering extensive design and manufacturing expenses.

These and other objects of this invention will appear hereinafter and for purposes of illustration, but not of limitation, specific embodiments of the invention are shown in the accompanying drawings in which:

FIG. 1 is a side elevational view illustrating a powder collecting means in conjunction with an electrostatic spraying system;

FIG. 2 is a plan view of the arrangement shown in FIG. 1;

FIG. 3 is a perspective view of a collecting module utilized in constructions of the type contemplated by the invention;

FIG. 4 is a bottom perspective view of the module shown in FIG. 3;

FIG. 5 is a perspective view of the module as shown in FIG. 4 with the deflector plates removed and with a wall portion partly cut away;

FIG. 6 is an enlarged cross-sectional view of the module taken about the line 6-6 of FIG. 4;

FIG. 7 is a cross-sectional view of the module provided with different deflector plates;

FIG. 8 is a perspective view of an exhaust manifold construction utilized in accordance with the concepts of the invention; and,

FIG. 9 is a vertical, sectional view of the manifold construction.

The construction of this invention is designed for use in a system wherein powder is sprayed or otherwise applied to a moving surface. The invention is specifically applicable to the collection of powder whereby undesirable amounts of powder can be prevented from entering the atmosphere surrounding the powder applying mechanisms.

The particular collecting means of the invention comprise modules which define enclosing walls including end walls and which are each provided with inlet and outlet openings. The modules are adapted to be mounted on a common support in end-to-end relationship, and conduits are connected to the outlets of each module. The conduits are in turn connected to a suction system whereby powder is adapted to be collected by the individual modules and then transported by the respective conduits to an area where the powder can be disposed of or utilized forother purposes.

By employing the individual modules which may be dimensioned with a length between about 8 to 12 inches, preferably 10 inches, 21 collection construction can be readily set up for powder applicators of different sizes. Thus, the arrangement of the invention provides for the mounting of the individual modules in end-toend relationship so that the length of the assembly of modules can be readily varied to suit a particular need.

The modules are preferably provided with deflector plates designed to direct powder through the module inlet openings. These deflector plates are adjustable and are preferably positioned along opposite edges of the inlet openings so that the size of the inlet openings can be varied to suit a particular need. In addition, sliding gate members are preferably associated with the module outlet openings so that the dimensions of these openings are also variable. Such variations are quite helpful in designing a particular module set-up since the collection function of individual nozzles in a single assembly can vary depending upon the particular application involved.

The invention also contemplates the provision of an exhaust manifold which is adapted to be connected with each conduit. The manifold structure permits the association of several conduits with a single exhaust pipe being employed for receiving all of the powder collected from the several conduits. The manifold design is such that two or more groups of modules can be provided at different locations around a powder applicator with all of the conduits extending from the modules to the same exhaust manifold.

In the drawings, FIGS. 1 and 2 illustrate a system including a powder applicator structure 10. The applicator structure, which would typically be an electrostatic powder sprayer, comprises a hopper 12, and a drive motor 14 which drives metering roll 16. As shown, powder drops downwardly from the sprayer toward the lower flight 18 of a conveyor. This conveyor is provided with a gripping means 20 of any conventional design whereby printed sheets 22 can be moved from a printing press (not shown) into position opposite the powder sprayer. When the anti-offset powder has been provided on the printed surface, the individual sheets are dropped by the gripping means into a stack located beneath the lower flight of the conveyor.

The powder collecting means of the invention includes a plurality of modules 24 positioned adjacent the applicator 12. These modules are attached to a rail 25 or other supporting means attached to frame means (not shown) so that the modules form an assembly extending across the conveyor for approximately the same distance as the powder sprayer.

Each module has attached thereto a conduit 26 with the conduit extending to an exhaust manifold 28. The exhaust manifold in turn is provided with a centrally located exhaust pipe 30. As shown, the conduits 26 extend outwardly beyond the sides of the upper flight 32 of the conveyor so that these conduits do not intefere with the conveyor movement.

A separate set of modules 24 may be mounted above the upper flight 32 of the conveyor, and separate conduits 36 are utilized for connecting these modules to the exhaust manifold 28. It will be appreciated that with the arrangement of the invention, the modules may be positioned at different locations depending upon the physical arrangement of the conveyor and applicator structures as well as the physical arrangement of the surrounding area. One alternative to the specific arrangement illustrated in FIG. 1 would be the location of an assembly of modules forwardly of the applicator with the motor 14 and associated mechanisms being relocated, if necessary, to provide an optimum location for these modules.

The modules 24 are designed to assume various positions and forms. As illustrated in FIGS. 3-7, the modules comprise a wall 38 for supporting cylindrical coupling element 47 and opposing wall. A short wall 40 is opposed by solid wall 42, and walls 44 are found at each end. The wall 38 defines a circular outlet opening communicating with coupling element 47 for passage of air and powder into an associated conduit. The conduit may be secured by press fitting or other conventional means.

A pair of sliding gates 48 are attached to the under side of the wall 38 by means of fasteners 50. These fasteners are received in slots 52 so that the gates can be moved to vary the effective size of the outlet opening.

In FIGS. 3, 4 and 6, deflector blades 54 and 56 are secured, respectively, to the walls 40 and 46 of the modules. Fasteners 58 are received in slots 60 defined by blade 54 whereby the position of this blade can be varied relative to the edge of the front wall 40. Similarly, fasteners and slots are utilized for securing blade 56 whereby the position of this blade can be adjusted relative to the position of bottom wall 46. The blades 54 and 56 serve to define inlet openings for each module, and the extension of one blade horizontally and the other vertically provides a funnel-like arrangement which will tend to direct large portions of airborne powder into the individual modules.

The modules 24 immediately adjacent applicator 12 are disposed as shown in FIG. 6 whereby the conduits extend from the sides of the modules. The attitude shown in FIG. 3 is also feasible where it would be more convenient to extend the conduits from the top of the modules, for example for space considerations. The deflector blades 54 and 56 are interchangeable so that if a particular application calls for one blade being longer than the other, then all of the same parts can be used for any position of the blades.

FIG. 7 illustrates a module 24 wherein a straight deflector blade 76 is attached by means of fasteners 78 to the side wall 40. A second straight deflector blade 84 is attached by means of fasteners 86 with the positions of both blades being adjustable. FIG. 1 illustrates an application of straight deflector blades 76 and 84 on modules 24. An angle 88 is provided for supporting this group of modules.

The straight blades 76 and 84 are preferably utilized as stock material for forming blades 54 and 56. It will be appreciated that this permits formation of deflecting surfaces of different sizes depending upon where a bend is made in the stock material. In addition, the angle of a bend can vary so that any application can be accommodated in the most efficient manner.

The described module configurations are designed for inclusion in an assembly with the end walls of the modules preferably located immediately adjacent each other. This permits efficient collection of powder due to the fact that each module can be individually adjusted so that greater or lesser collection can be attained at different points along the length of the assembly. This can be particularly effective where the nonuniform suction will tend to increase the percentage of powder collected, and a degree of experimentation can determine the most efficient arrangement after a module assembly has been set up.

The exhaust manifold 28 is illustrated in detail in FIGS. 8 and 9. This manifold defines downwardly extending top surfaces 94 on either side of the exhaust pipe 30, and a plurality of openings 96 are defined by each top wall. Coupling elements 98 are utilized for attaching the ends of conduits 26 and 36 extending from the modules 24. The bottom wall 100 preferably peaks beneath the exhaust pipe 30 to direct powder entering the manifold upwardly into the pipe.

The coupling elements 98 are preferably formed on plates 102 which can be attached to the manifold to span large openings in the manifold top walls. As illustrated in FIG. 8, provision is made at 104 for removing additional sections of the top wall whereby additional plates 102 can be added to thereby increase the number of conduits directed to the exhaust manifold. Thus, the design of the exhaust manifold adds further to the versatility of the system by providing, in the embodiment illustrated, for the connection of as many as 16 conduits.

The exhaust manifold is supported on a plate 106 which is positioned above the upper flight 32. This plate serves as a housing portion tending to prevent airborne particules from rising about the level of the plate.

One or more gates 108 are provided for the plate 106 to provide access to the assembly of modules 24 and to the applicator structure. Otherwise the plate 106 defines appropriate openings for mounting of the upper assembly of modules while also providing a suitable mounting surface for the exhaust manifold.

It has been found that the structures described are exceptionally effective for purposes of collecting particulate material particularly the material in the 5 to 20 microns range which represents the most troublesome material. This collection is accomplished without disrupting the passage of the larger particles onto the moving surfaces.

The structures of this invention do not require the massive amounts of air and large blower and energy outputs which characterize other systems. Where large displacements of air are required, it has been found that the sheet delivery systems and the powder application to the sheets can be adversely affected unless the removal means are located in out of the way positions so that large amounts of the troublesome particles cannot be collected.

By utilizing individual modules in the order of inches long, various module assemblies can be obtained without any significant increase in manufacturing and assembly costs. Thus, custom collection system can be provided without the necessity for the custom design of air nozzles, exhaust manifolds, etcetera.

In applicants arrangement wherein the collection assemblies are located closely adjacent the powder delivery hopper as shown in FIG. 1, the nuisance powder is collected before being distributed into the surrounding atmosphere. A low amount of suction is required because of the proximity of the module assembly thereby reducing the power requirements as well as the volume of air in the collection system.

Although the arrangement ofFIG. 1 is preferred, the utilization of only an upper module assembly can be effective where space limitations prevent the insertion of the lower assemblies. As noted, the addition of other module assemblies at other locations is also contemplated. Such additions can include mounting of a module assembly underneath the hopper below the lower conveyor flight.

It will be understood that various changes and modifications may be made in the above described construction which provide the characteristics of the invention without departing from the spirit thereof particularly as defined in the following claims.

That which is claimed is:

1. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a plurality of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module, means supporting the modules in end-to-end assembly adjacent said applicator, the assembly of nozzles extending substantially across said moving surface, individual conduits connected to each of said outlet openings, and suction means connected to said conduits whereby powder in the air around the applicator is pulled simultaneously into the respective inlet openings and collected through said conduits.

2. A construction in accordance with claim 1 including deflector blades attached to said modules, said blades extending outwardly on opposite sides of said inlet openings.

3. A construction in accordance with claim 1 wherein said modules have a length between about 8 and 12 inches.

4. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a plurality of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module, a pair of deflector blades attached to the walls of each module, said walls defining the module inlet opening therebetween, said blades extending outwardly on opposite sides of each inlet opening away from the edges of the inlet opening to increase the collecting ability of the modules, means supporting the modules in end-to-end relationship adjacent said applicator, individual conduits connected to each of said outlet openings, and suction means connected to said conduits whereby powder in the air around the applicator is pulled into the respective inlet openings and collected through said conduits.

5. A construction in accordance with claim 4 including means for adjusting the positions of said blades relative to the edges of said inlet openings.

6. A construction in accordance with claim 5 wherein said blades are produced from stock of a standard size, said stock being bendable whereby the size and position of the blade surface engaged by air and powder can be varied.

7. A construction in accordance with claim 4 wherein said blades are bent angularly away from the walls to which they are attached.

8. A construction in accordance with claim 4 wherein said blades extend parallel with the walls to which they are attached.

9. A construction in accordance with claim 4 wherein each module comprises a pair of first walls positioned at right angles, one of said first walls defining said outlet opening, said walls defining the inlet opening comprising short walls formed integrally with said first walls and a right angle thereto.

10. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a plurality of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module, means supporting the modules in end-to-end relationship adjacent each said applicator, individual conduits connected to each of said outlet openings, and suction means connected to said conduits whereby powder in the air around the applicator is pulled into the respective inlet openings and collected through said conduits, said means for supporting said plurality of modules being located close to the path of movement of said moving surface, and including a second set of modules, means supporting said second set in a location remote from said applicator, and including individual conduits for connecting the outlet openings of said second set of modules to said suction means.

11. A construction in accordance with claim 10 wherein said suction means comprises an exhaust manifold, a plurality of inlet openings for said manifold, and means for connecting each conduit to one of said manifold inlet openings.

12. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a plurality of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module, means supporting the modules in end-to-end relationship adjacent said applicator, in-

dividual conduits connected to each of said outlet openings, suction means connected to said conduits whereby powder in the air around the applicator is pulled into the respective inlet openings and collected through said conduits, and including means for adjusting the size of said module openings to thereby permit variations in the degree of suction applied to a particular module.

13. A construction in accordance with claim 12 wherein said oulet openings comprise relatively small openings in the side walls of said modules, and including adjustable plates attached to said side walls and movable into partially blocking positions relative to the outlet openings for varying the effective size of said openings.

14. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, a conveyor for moving said surface past said applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a plurality of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module means supporting the modules in end-to-end relationship adjacent said applicator, individual conduits connected to each of said outlet openings, suction means connected to said conduits whereby powder in the air around the applicator is pulled into the respective inlet openings and collected through said conduits, and wherein said applicator and the adjacent modules are positioned immediately above the lower flight of said conveyor, said conduits extending around the upper flight of the conveyor, said suction means being positioned above said upper flight.

15. A construction in accordance with claim 14 wherein said suction means includes an exhaust manifold defining inlet openings for the attachment of said conduits, said manifold defining a centrally located exhaust pipe with said inlet openings of the manifold being provided on both sides of said pipe.

16. A construction in accordance with claim 5 including a support plate positioned above said upper flight for blocking the passage of powder, said exhaust manifold being positioned on said support plate, and including a second set of said modules supported by said support plate with additional conduits extending from the outlet openings of said modules to said exhaust manifold.

17. A construction in accordance with claim 16 including doors carried by said support plate to permit access to said applicator and modules positioned beneath the support plate.

18. A construction in accordance with claim 15 wherein said manifold defines top surfaces extending downwardly on opposite sides of said exhaust pipe, said surfaces providing for the formation of a plurality of manifold inlet openings with the number of the openings depending upon the number of conduits attached to the manifold, and including a bottom wall portion for the manifold extending upwardly to a peak centrally of said exhaust pipe for directing powder from said inlet openings to said exhaust pipe. 

1. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a plurality of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module, means supporting the modules in end-to-end assembly adjacent said applicator, the assembly of nozzles extending substantially across said moving surface, individual conduits connected to each of said outlet openings, and suction means connected to said conduits whereby powder in the air around the applicator is pulled simultaneously into the respective inlet openings and collected through said conduits.
 2. A construction in accordance with claim 1 including deflector blades attached to said modules, said blades extending outwardly on opposite sides of said inlet openings.
 3. A construction in accordance with claim 1 wherein said modules have a length between about 8 and 12 inches.
 4. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a plurality of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module, a pair of deflector blades attached to the walls of each module, said walls defining the module inlet opening therebetween, said blades extending outwardly on opposite sides of each inlet opening away from the edges of the inlet opening to increase the collecting ability of the modules, means supporting the modules in end-to-end relationship adjacent said applicator, individual conduits connected to each of said outlet openings, and suction means connected to said conduits whereby powder in the air around the applicator is pulled into the respective inlet openings and collected through said conduits.
 5. A construction in accordance with claim 4 including means for adjusting the positions of said blades relative to the edges of said inlet openings.
 6. A construction in accordance with claim 5 wherein said blades are produced from stock of a standard size, said stock being bendable whereby the size and position of the blade surface engaged by air and powder can be varied.
 7. A construction in accordance with claim 4 wherein said blades are bent angularly away from the walls to which they are attached.
 8. A construction in accordance with claim 4 wherein said blades extend parallel with the walls to which they are attached.
 9. A construction in accordance with claim 4 wherein each module comprises a pair of first walls positioned at right angles, one of said first walls defining said outlet opening, said walls defining the inlet opening comprising short walls formed integrally with said first walls and a right angle thereto.
 10. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a pluralIty of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module, means supporting the modules in end-to-end relationship adjacent each said applicator, individual conduits connected to each of said outlet openings, and suction means connected to said conduits whereby powder in the air around the applicator is pulled into the respective inlet openings and collected through said conduits, said means for supporting said plurality of modules being located close to the path of movement of said moving surface, and including a second set of modules, means supporting said second set in a location remote from said applicator, and including individual conduits for connecting the outlet openings of said second set of modules to said suction means.
 11. A construction in accordance with claim 10 wherein said suction means comprises an exhaust manifold, a plurality of inlet openings for said manifold, and means for connecting each conduit to one of said manifold inlet openings.
 12. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a plurality of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module, means supporting the modules in end-to-end relationship adjacent said applicator, individual conduits connected to each of said outlet openings, suction means connected to said conduits whereby powder in the air around the applicator is pulled into the respective inlet openings and collected through said conduits, and including means for adjusting the size of said module openings to thereby permit variations in the degree of suction applied to a particular module.
 13. A construction in accordance with claim 12 wherein said oulet openings comprise relatively small openings in the side walls of said modules, and including adjustable plates attached to said side walls and movable into partially blocking positions relative to the outlet openings for varying the effective size of said openings.
 14. In a system for applying powder to a moving surface wherein the powder is sprayed from an applicator, a conveyor for moving said surface past said applicator, the improvement comprising means located adjacent the applicator for collecting excess powder from around the applicator to thereby reduce the presence of the powder in the surrounding atmosphere, said collecting means comprising a plurality of modules, each module comprising enclosing walls including end walls and interconnected side walls, inlet and outlet openings defined by each module means supporting the modules in end-to-end relationship adjacent said applicator, individual conduits connected to each of said outlet openings, suction means connected to said conduits whereby powder in the air around the applicator is pulled into the respective inlet openings and collected through said conduits, and wherein said applicator and the adjacent modules are positioned immediately above the lower flight of said conveyor, said conduits extending around the upper flight of the conveyor, said suction means being positioned above said upper flight.
 15. A construction in accordance with claim 14 wherein said suction means includes an exhaust manifold defining inlet openings for the attachment of said conduits, said manifold defining a centrally located exhaust pipe with said inlet openings of the manifold being provided on both sides of said pipe.
 16. A construction in accordance with claim 5 including a support plate positioned above said upper flight for blocking the passage of powder, said exhaust manifold being positioned on said support plate, and including a second set of saId modules supported by said support plate with additional conduits extending from the outlet openings of said modules to said exhaust manifold.
 17. A construction in accordance with claim 16 including doors carried by said support plate to permit access to said applicator and modules positioned beneath the support plate.
 18. A construction in accordance with claim 15 wherein said manifold defines top surfaces extending downwardly on opposite sides of said exhaust pipe, said surfaces providing for the formation of a plurality of manifold inlet openings with the number of the openings depending upon the number of conduits attached to the manifold, and including a bottom wall portion for the manifold extending upwardly to a peak centrally of said exhaust pipe for directing powder from said inlet openings to said exhaust pipe. 